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Problem 2. A long thin alloy wire with a diameter of 0.2 mm is exposed to...
Inside the chamber is a horizontal long resistor wire having a diameter of 2.5 mm. The...
Inside the chamber is a horizontal long resistor wire having a diameter of 2.5 mm. The chamber the internal surfaces have a constant temperature of 280 K and the temperature of the air inside the chamber is 300 K. The emissivity of the outer surface of the resistor is ε = 0.3 and the specific resistance R '= 2.162 Ω/ m. The resistance the maximum surface temperature must not exceed 1500 K. Calculate the current flowing through the resistor maximum...
5. Problem 3.54 (Textbook) (20 points) KNOWN: Diameter of electrical wire. Thickness and thermal conductivity of...
5. Problem 3.54 (Textbook) (20 points) KNOWN: Diameter of electrical wire. Thickness and thermal conductivity of rubberized sheath. Contact resistance between sheath and wire. Convection coefficient and ambient air temperature. Maximum allowable sheath temperature. FIND: Maximum allowable power dissipation per unit length of wire. Critical radius of insulation. SCHEMATIC: Air Wire Egen. D-2 mm Two Tini Tino To Ric = 3x10-4 m2-KW Insulation, t = 2 mm T= 20°C Ric Rcond conv k = 0.13 W/m-K Tmax = 50°C h...
A 2.2-mm-diameter and 10-m-long electric wire is tightly wrapped with a 1-mm-thick plastic cover whose thermal...
A 2.2-mm-diameter and 10-m-long electric wire is tightly wrapped with a 1-mm-thick plastic cover whose thermal conductivity is k0.15 W/m-K. Electrical measurements indicate that a current of 13 A passes through the wire and there is a voltage drop of 8 V along the wire. If the insulated wire is exposed to a medium at T 30°C with a heat transfer coefficient of h 24 W/m2 K, determine the temperature at the interface of the wire and the plastic cover...
2-157 A long electrical resistance wire of radius r.-0.25 cm has a thermal conductivity kwire-15 W/m-K. Heat is gene...
2-157 A long electrical resistance wire of radius r.-0.25 cm has a thermal conductivity kwire-15 W/m-K. Heat is generated uniformly in the wire as a result of resistance heating at a constant rate of 0.5 W/cm3. The wire is covered with polyethylene insulation with a thickness of 0.25 cm and thermal conductivity of ks 0.4 W/m K. The outer surface of the insulation is subjected to free convection in air at 20°C and a convection heat transfer coefficient of 2...
1. Consider an opaque, horizontal square plate (Im by 1m) with an electrical heater on its backside. The front side is exposed to ambient quiescent air that is at 20° C, solar irradiation (from...
1. Consider an opaque, horizontal square plate (Im by 1m) with an electrical heater on its backside. The front side is exposed to ambient quiescent air that is at 20° C, solar irradiation (from sun at 5800° K) of 600 W/m2, and an effective sky temperature of -40° C. The plate surface temperature is kept at Ts 60 C (at steady state condition). Calculate natural convection heat transfer coefficient from the plate. (10 points) What is the electrical power (W/m2)...
A brass rod (k = 133 W/m-K) with a diameter of 5 mm and a length...
A brass rod (k = 133 W/m-K) with a diameter of 5 mm and a length of 100 mm is used to enhance heat transfer from a surface which is maintained at 200 C. The cylindrical surface of the rod is exposed to a convection environment with h = 30 W/m2-K and an ambient temperature of 20 C. a) Calculate the heat convected away from the rod. b) Calculate the temperature 50 mm from the wall. c) Plot the temperature...
Please help me with this problem 2. A composite cylinder is formed by a long cylindrical...
Please help me with this problem
2. A composite cylinder is formed by a long cylindrical rod (A) and two concentric cylinders (tubes B and C). Tube B encloses trod A and its inner and outer radii are 20 mm and 40 mm, respectively. Tube C encloses tube B and its outer radius is 50 mm. A thin electrical heater is inserted between rod A and tube B. The rod (A) has a thermal conductivity of 2.5 w/m K, while...
A long wire with circular cross section and diameter D = 1 mm is submerged in an oil bath with temperature To 20。C. The wire is initially at temperature T = 20。C, the same temperature as the oil. A...
A long wire with circular cross section and diameter D = 1 mm is submerged in an oil bath with temperature To 20。C. The wire is initially at temperature T = 20。C, the same temperature as the oil. A current is passed through the wire, resulting in a volumetric heat generation of q - 1.5 x 108 W/m3. The convection coefficient is h - 500 W/m2 - K, and the properties of the wire are ρ-8000 kg/m3, Cp-500 J/kg-K, and...
An aluminum plate with a thickness of L=5 mm is mounted in a horizontal position, and...
An aluminum plate with a thickness of L=5 mm is mounted in a horizontal position, and its bottom surface is well insulated. A special, thin coating (with emissivity and solar absorptivity of 0.25) is applied to the top surface. The density ρ and specific heat c of aluminum are known to be 2700 kg/m3 and 900 J/kg · K, respectively. Consider conditions for which the plate is initially at a temperature of ??????=25 °C and its top surface is suddenly...
1: A horizontal, opaque flat surface at a steady-state temperature of 77C is exposed to an...
1: A horizontal, opaque flat surface at a steady-state temperature of 77C is exposed to an airflow having a freestream temperature of 27C with a velocity of 15 m/s, and a length of 1 m along the flow direction. The emissive power of the surface is 628 W/m2 , the irradiation from surroundingsis 1380 W/m2 , and the reflectivity is ?=0.40. (a) Determine the absorptivity (?) of the surface. Ans: 0.6 (b) Determine the net radiation heat transfer rate for...
5. Problem 3.54 (Textbook) (20 points) KNOWN: Diameter of electrical wire. Thickness and thermal conductivity of rubberized sheath. Contact resistance between sheath and wire. Convection coefficient and ambient air temperature. Maximum allowable sheath temperature. FIND: Maximum allowable power dissipation per unit length of wire. Critical radius of insulation. SCHEMATIC: Air Wire Egen. D-2 mm Two Tini Tino To Ric = 3x10-4 m2-KW Insulation, t = 2 mm T= 20°C Ric Rcond conv k = 0.13 W/m-K Tmax = 50°C h...
A 2.2-mm-diameter and 10-m-long electric wire is tightly wrapped with a 1-mm-thick plastic cover whose thermal conductivity is k0.15 W/m-K. Electrical measurements indicate that a current of 13 A passes through the wire and there is a voltage drop of 8 V along the wire. If the insulated wire is exposed to a medium at T 30°C with a heat transfer coefficient of h 24 W/m2 K, determine the temperature at the interface of the wire and the plastic cover...
2-157 A long electrical resistance wire of radius r.-0.25 cm has a thermal conductivity kwire-15 W/m-K. Heat is generated uniformly in the wire as a result of resistance heating at a constant rate of 0.5 W/cm3. The wire is covered with polyethylene insulation with a thickness of 0.25 cm and thermal conductivity of ks 0.4 W/m K. The outer surface of the insulation is subjected to free convection in air at 20°C and a convection heat transfer coefficient of 2...
1. Consider an opaque, horizontal square plate (Im by 1m) with an electrical heater on its backside. The front side is exposed to ambient quiescent air that is at 20° C, solar irradiation (from sun at 5800° K) of 600 W/m2, and an effective sky temperature of -40° C. The plate surface temperature is kept at Ts 60 C (at steady state condition). Calculate natural convection heat transfer coefficient from the plate. (10 points) What is the electrical power (W/m2)...
Please help me with this problem
2. A composite cylinder is formed by a long cylindrical rod (A) and two concentric cylinders (tubes B and C). Tube B encloses trod A and its inner and outer radii are 20 mm and 40 mm, respectively. Tube C encloses tube B and its outer radius is 50 mm. A thin electrical heater is inserted between rod A and tube B. The rod (A) has a thermal conductivity of 2.5 w/m K, while...
A long wire with circular cross section and diameter D = 1 mm is submerged in an oil bath with temperature To 20。C. The wire is initially at temperature T = 20。C, the same temperature as the oil. A current is passed through the wire, resulting in a volumetric heat generation of q - 1.5 x 108 W/m3. The convection coefficient is h - 500 W/m2 - K, and the properties of the wire are ρ-8000 kg/m3, Cp-500 J/kg-K, and...
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